The following invention relates to improvements in automatic saw sharpening machines of the type that grind the teeth of circular saws and the like from the side using a pair of grinding wheels.
An automatic dual side grinding machine is disclosed in the aforementioned co-pending U.S. patent application Ser. No. 788,925. That application discloses an automatic dual side grinder for circular saws and the like which includes a pair of spindles carrying rotary grinding wheels which are moved longitudinally into engagement with the teeth of a circular saw. The saw is mounted in the vertical plane and the grinding wheels traverse the sides of the saw teeth with a horizontal motion provided by a tie rod connected to a rotary cam which pushes a spindle assembly driving the wheels into engagement with these saw teeth. This is a reciprocating longitudinal motion and, under normal operation, the saw teeth are ground on the forward stroke and then the grinding wheels retract so that the blade may be automatically rotated by an indexing mechanism to present another tooth for grinding.
The indexing mechanism includes a finger which acts as a stop by engaging the scalloped outer portions of the blade which hold the carbide tips of saw teeth. A piston and cylinder drives a rotary shaft on which the blade is mounted to cause it to rotate until it engages the indexing finger.
There are two adjustments which are critical to proper sharpening of the saw teeth and both concern the position of the grinding wheels relative to the teeth. The first adjustment is called the tangential angle adjustment and relates to the vertical position of the grinding wheels with respect to each saw tooth. The saw teeth have a trapezoidal cross section and in saw regrinding, a choice can be made as to whether the grinding wheels will grind high or low on the sides of the teeth. In the past, the tangential angle adjustment has been made by adjusting the angle of the index finger relative to vertical. This was done by tightening a bolt which engaged the forward surface of the index finger causing it to pivot about a pin. This arrangement is unsatisfactory because the adjustment is not precise enough to meet the needs of current users of circular saws.
Another adjustment is termed the radial angle adjustment, in which the angle of attack between the grinding wheels and the saw teeth in the horizontal plane is altered. In the horizontal plane, the grinding wheels may be tilted off-axis (the axis of longitudinal motion) so that the saw teeth are ground at a slight angle. Nominally the longitudinal motion of the grinding wheels, which occurs in the horizontal plane, is parallel to the saw blade. The radial angle adjustment alters this so that the longitudinal movement of the grinding wheels may be offset slightly with respect to the plane of the saw blade. In the past this adjustment has been accomplished by loosening bolts which hold drive spindles mounted on plates attached to the frame so that the plates could be moved relative to the frame. A lack of precision has made this method of making the radial angle adjustment unsatisfactory.